Apparatus for indicating the rate of a flow of a fluid



Nov. 1l, 1958 l H. FELLows 2,859,616

APPARATUS FOR INDICATI-.NG THE RATE OF A FLOW OF A FLUID Filed Feb. 1, 1956 2 Sh'eetSLSheet 1 rl stages lill:

JAM-Ma l max Nov. 1'1, 1958 H. FELLows 2,859,516

APPARATUSl FIOR INDICATING THE RATE OE' A.FI..OW OF A FLUID Filed Feb. 1', 195e l 2 sheets-sheet 2 v ng. 3.

United States PatentA APPARATUS FOR INDICATING THE RATE OF A FLOW F A FLUID Horace Fellows, Wolverhampton, England, assignorto H. M. Hobson Limited, London, England, a British company Application February 1, 1956, Serial No. 562,869

Claims priority, application Great Britain March 7, 1955 3 Claims. (c1. '7s-195) of fuel flow as indicated by a corresponding number of similar flowmeters vof the above type.

The ratemeter according to the invention comprises a plurality of mono-stable tlip-tlops of the same `time constant, one associated with each ilowmeter, means for applying the pulses from each of the ilowmeters to a control electrode of the normally non-conducting section of the associated flip-flop, and a device for measuring the current in an anode circuit common to the aodes of the normally non-conducting sections of all of the flip-flops.

One specific embodiment of summation device according to the invention will now be described in more detail, by way of example, with reference to the accompanying drawings in which:

Fig. 1 is a circuit diagram of the ratemeter,

Fig. 2 shows diagrammatically the wave forms of certain pulses and the current measured by the current measuring device, and

Fig. 3 is a block diagram showing two owmeters, the common ratemeter and a common mechanism for summing on a counter the quantities of fuel or other liquid traversing the two owmeters.

The two fiowmeters 10, A shown in Fig. 3 are of similar construction, the transmitter of each producing the same number of pulses per unit quantity of liquid flowing. Parts of the iiowmeter 10A bear the same reference numerals as the corresponding parts of the llowmeter 10, with the addition of the sux A.

The owmeter 10 comprises a vaned rotor 11 mounted for rotation within and about the axis of a conduit 12 through which liquid is flowing. The rotor 11 carries a magnet 13 which, as the rotor rotates, generates electrical pulses in a pick-up 14 external to the conduit 12. The pulses so generated are amplified by an ampliier 15 and converted by a Shaper stage 16 into short pulses of the wave form indicated at esl in Fig. 1. The pulses from the two shaper stages 16, 16A are passed to a common ratemeter 17 of the construction shown in detail in Fig. l.

As indicated in Fig. l, the ratemeter comprises two mono-stable ip-tlops V1, V2 of the same time constant and each consisting of two triodes in a common envelope. The normally non-conducting section of each ipop is marked A and its normally conducting section is marked B.

Positive pulses egl of repetition rate f1 are applied from the Shaper stage 16 to the grid of the normally non-conducting section A of the ip-op V1, and positive pulses e811 of repetition rate f2 are applied from 2,859,616 Patented Nov. ll, 1958 "ice , 2 the other shaper stage 16A to the grid 'of the normally non-conducting section A of the ilip-flop V2. Each pulse applied to the grid of valve V1A will produce 'at its anode a1 a positive current pulse of amplitude a1 max., and of width t, provided T, which equals 1 f1 secs., is greater 'than t, the mark time of the ipjop. The unstable regime of the circuit has been so designed that over the working frequency range T is always greater than t.

Similarly the pulses applied to the grid of valve V2A produce at its anode an pulses of amplitude au max.=a1 max.

and width t.

An average reading milliammeter M, common to these two anode circuits, will record a current Im which is the sum of the mean values a1 av. and au av. of the anode signal currents of the valves VlA and V2A.

This is illustrated in Fig. 2, in which a and b respectively indicate the pulses applied to the grids of the valves V1A and V2A, c and d respectively indicate the pulses appearing at their anodes and e indicates the meter current Im.

As will readily be understood, summation of more than two rates of tlow may be achieved by adding the appropriate number of additional ip-flops, the pulses from their associated owmeters being applied to the grids of their A sections and the meter M being con nected in the common anode circuit of-the A sections of all the ip-flops.

A three position selector switch S is provided. When this is on its central contact 3, as shown, the milliammeter M operates to sum the two instantaneous rates of flow as already described. If the switch S is moved to its contact 1, it grounds the input to the grid of valve VIA, so short-circuiting the llip-llop V1 and causing the milliammeter M to record only the ow measured by the flowmeter associated with the flip-flop V2. Similarly, movement of the switch S to its contact 2 short circuits the input to the flip-Hop V2 and the milliamrneter then records only the ov/ measured by the lowmeter associated with the flip-flop V1.

As indicated in Fig. 3, provision may also be made for summing on a counter 18 the quantities of liquid traversing the two owmeters 10, 10A. To this end, the Shaper stages 16, 16A are connected by a pulse gating circuit 19 and a buffer stage 20 to the rst, 21, of a chain of n electronic binary frequency dividers. The pulses from the last frequency divider 21n actuate a driver stage 22 for the counter 18.

Each of the Shaper stages 16, 16A is constituted by a mono-stable flip-Hop and positive trigger pulses are supplied from the cathode resistor of this llip-op to the ratemeter 17. Negative pulses are supplied from the anode of the normally conducting section of each Shaper ilip-tlop to the pulse gating circuit 19, which includes the diodes 23, 23A which pass negative pulses, via the buffer stage 20, to the first binary frequency divider. The frequency dividers are Hip-flops of the Eccles-Jordan type and the driver stage 22 comprises an amplifier having, in its anode circuit, a solenoid for actuating the counter.

i The apparatus thus enables one counter 18 and one meter M to display the following:

(1) Fuel consumed and rate of fuel consumption of Atwo aircraft engines.

,y 4(2) Fuel consumed and rate of fuel consumption of twq aircraft reheat systems.

(3) Fuel consumed and rate of fuel consumption of one aircraft engine and one aircraft reheat system.

It will be appreciated that it is necessary, in order to permit of summation of rates of ow to a single ratemeter, that the twoowmeters 10, 10A should be similar, i. e. that they should perform equal numbers of revolutions per unit quantity of fuel iiow through their ,respective conduits.

What I claim as my invention and desire to secure by ILetters Patent is:

1. The combination, with a plurality of uid ilowmeters each comprising an electrical transmitter arranged to generate electrical pulses at a repetition frequency determined by the instantaneous rate of ow of iiuid measured by said owmeter, of a ratemeter common to all of said owmeters, said ratemeter comprising a plurality of mono-stable ip flops one connected to each tlowmeter, each flip-Hop having a normally conducting section and a normally non-conducting section, both sections of each ip-op having an anode and a control electrode and all of said ip-flops having the same time constant'and a mark time less than the reciprocal of ythe repetition frequency of the pulses generated by any of said owmeters, means for applying the pulses from each of the fiowmeters to 4the control electrode of the normally non-conducting section of the associated flip` flop and a current measuring device connected in an anode circuit common to the normally non-conducting sections of all of the flip flops and responsive to the sum of the currents owing in all of said normally non-conducting sections.

2. Apparatus as claimed in claim l, wherein each flowmeter comprises a magnetized rotor mounted for rotation in a conduit for the passage of uid, a co-operating coil external to the conduit, an ampliiier'for the pulses generated in the coil by the rotation of said rotor and a shaper stage for shaping the amplified pulses produced by the amplifier, the shaped pulses delivered by the shaper stages being applied to said control electrodes of the ratemeter flip-flops.

3. Apparatus as claimed in claim 2, comprising an electro-mechanical counter, a chain of binary electronic frequency dividers, and means for supplying pulses from all of the shaper stages to the first divider of the chain, the counter being actuated by the last divider of the chain.

References Cited in the file of this patent UNlTED STATES PATENTS 1,614,217 Thompson Jan. 11, 1927 2,270,141 Potter Ian. 13, 1942 2,325,927 Wilbur Aug. 3, 1943 2,420,539 Hornfeck May 13, 1947 2,683,224 Cole July 6, 1954 2,724,270 Trekell Nov. 22, 1955 OTHER REFERENCES Pages 414-420 Active Networks by Rideout, published 1954 by Prentice-Hall, New York. 

